With improvements in the performance of portable devices having an image pickup function and small-size optical apparatuses such as micro video scopes in recent years, there are demands for improvements of the optical components such as lenses, stops and optical filters used therein. Specifically, there are increasing demands for replacement of conventional fixed focal length lenses, fixed aperture stops, and optical filters having fixed characteristics respectively with adjustable focus lenses, variable stops, and optical filters having variable characteristics, and various techniques for reducing the sizes of optical components used in small-size image pickup devices have been developed.
FIG. 9 is a plan view showing the construction of a conventional electromagnetic driving apparatus. In the electromagnetic driving apparatus shown in FIG. 9, which is taught by patent literature 1, a taking lens 902 is held by a base plate 901, and a coil core (yoke) 903 arranged around the taking lens 902 and a magnet (permanent magnet) 905 forma closed magnetic circuit. The two ends 903a, 903b of the coil core 903 are opposed to the magnet 905. A winding coil 904 for energizing is wound around the coil core 903. The arrangement of the winding coil on the base plate in this construction allows a reduction in the diameter of the apparatus.